Many different types of mechanical, electromechanical, and electronic display devices are known in the Prior Art. For example, Wakatake U.S. Pat. No. 4,177,458, a display panel, is shown to include a plurality of display elements that are rotatable in a vertical plane. The elements are formed from plate-like or four-cornered block members having two or four display surfaces of different colors and include one or three magnetic pieces, respectively. Up to three electromagnets are energized for permitting the selection of a particular face of a given display element be rotated to the display side of the display panel. In this manner a desired pattern can be displayed. In a later Wakatake U.S. Pat. No. 4,264,906, similar display elements are shown that have display surfaces of different colors, performing displays of desired characters or patterns in the display side of the display panel.
In Bergamin; U.S. Pat. No. 4,161,832, an electromechanical digital indicator for displaying numerical information is disclosed, in which angular movements of seven movable segments are combined with the action of a block in the shape of an eight and made of a transparent and light-channeling plastic material, to display selected figures from zero to nine in solid lines rather than in segmented form. Fluorescent layers on the bottom wall of the block are included for displaying the numerals under conditions of either direct or indirect lighting, or in darkness. Also, internal illumination can be provided on the interior portion of the indicator box.
In Andersen U.S. Pat. No. 4,091,382, a display system is disclosed that is made up of a plurality of display units each including a thin, pivotally-mounted vane 20 movable by electrostatic forces between an upright and a horizontal position, for selectively providing a desired display. Also, in Winrow U.S. Pat. No. 3,975,728, an electromagnetic display is taught that includes a plurality of display elements each including a disc that is pivotally mounted on an axis parallel to the mean plane of the display, whereby electromagnetic means are used to rotate the disc for providing a desired display. In Hart U.S. Pat. No. 3,685,040, a display apparatus including a plurality of horizontally extending panels interconnected to form an endless belt having a plurality of light passages, wherein each light passage includes a closure mechanism for selectively opening or closing the light passageway, whereby lamps positioned on the nondisplay side of the belt are selectively permitted to shine light through the passages passing in front of the lamps for displaying desired information on the display side of the apparatus area. Another display device for covering or uncovering a display element includes shutter disc or shutter blades electromechanically operable to cover or uncover a hole for displaying information, as taught in Salam U.S. Pat. No. 3,562,938.
In Levy et al. U.S. Pat. No. 3,267,595, a display unit is disclosed that can be provided with a plurality of different types of display elements and triggering mechanisms for moving the display elements to change the display. In one embodiment, Levy et al. includes a moving belt of rows and columns of rotatable rectangular-like display elements, whereby for each row of display elements, a solenoid-operated trigger finger is selectively activated for flipping over (rotating by 180.degree. selective ones of the elements for changing the information being displayed. A mechanical cam mechanism 24 (see FIG. 6) is used to hold a given display element 23 in appropriate alignment in the display for displaying information through appropriate positioning of the various ones of the elements 23 in the matrix. In FIG. 8, a control system is shown for controlling selective activation of the various electromagnetic triggers for selectively flipping the display elements 23. In another embodiment, triangular display elements are shown in FIG. 9 for providing three-faced elements, and are used in combination with a pair of solenoid-operated trigger pins to rotate selected ones of the triangles from one display position to another. Four-faced display elements 60, as shown in FIG. 11, represent another embodiment which requires three solenoid-operated "triggers" for selectively rotating a given four-faced element or block, and three "reset fingers" are required for resetting the elements. Each element of Levy's four-faced elements appear to be cube-like, and to have four unique faces. Also, Levy rotates the belt of display elements past stationery solenoid-operated triggers for changing the elements rotational orientation, to change a given display. Another embodiment of Levy et al. (see FIG. 26) shows a fixed matrix of display elements 160, with a carriage mechanism provided at the back of the display 160, for moving a plurality of solenoid-operated fingers back and forth across the back of the display element, for selectively flipping various ones of the display elements 180.degree. for providing a desired display on the front of the display unit. As shown in FIG. 27, the elements 161 each include two lugs for providing automatic resetting, whereby when a given one of the lugs 175 or 176 contact an arm 171 of a solenoid 172, the element is flipped 180.degree. to change the face of the element being presented on the display side of the display unit.
A display apparatus using selectively rotatable spheres mounted on rods, whereby half of a given sphere is one color, and the other half another color. The spheres are selectively rotated to display information in a matrix of two colors. Also, in Roberts U.S. Pat. No. 4,139,841, an electromagnetic display board is taught having a plurality of holes arranged in rows and columns, sources of light behind the holes, and electromagnetically-operated shutters for opening and closing each hole for displaying desired information.